Though clearly beneficial, the use of methadone during pregnancy remains controversial in part to the large percentage [of newborns having signs of opioid withdrawal requiring medical intervention and extended hospitalization. A new [medication, buprenorphine, is approved by the Food and Drug Administration (FDA) for the treatment of non-pregnant opioid dependent patients and produces only a mild abstinence syndrome following abrupt withdrawal. Promising preliminary data from a double-blind randomized trial at the Johns Hopkins School of Medicine (JEUSOM) have directed this revised application and suggest that buprenorphine results in less neonatal abstinence syndrome (NAS) and improved birth outcomes relative to methadone. The proposed randomized, parallel group study will be the first multi-site trial to assess in opioid-dependent pregnant women the efficacy of buprenorphine for reducing NAS relative to methadone. JHUSOM is the Lead Site for this study involving five U.S. and two international sites. The Vienna team skilled in addiction medicine, psychiatry, pediatrics, obstetrics, neonatology, and controlled clinical trials will assure comprehensive oversight and rigorous scientific integrity of the study, Opioid-dependent pregnant women will be randomized to optimal doses of buprenorphine (n=26) or methadone (n=26) and followed throughout pregnancy. Treatment groups will be compared on the primary outcome measures of peak total NAS score; number of neonates treated for NAS; total amount of anti-withdrawal medication given to neonates treated for NAS; physical birth parameter of head circumference; and neonatal length of hospital stay. Secondary neonatal/fetal outcome measures include other physical, behavioral and safety parameters. Secondary maternal outcomes include treatment retention, drug use, medication safety, psychosocial functioning and dose adequacy. This first study will establish an infrastructure and network with expertise in conducting controlled trials with pharmacotherapies for substance dependent pregnant women. Overall, this study will provide pivotal data to the FDA to support an indication for the use of buprenorphine during pregnancy and potentially optimize strategies for safe and effective treatment of pregnant opioid-dependent women.